rohm &hass chemicals for water treatment(2)

KATHON™ WT Water Treatment Microbicide
Description
KATHON WT*,WTE and WTA microbicides are high performance, broad spectrum, antimicrobial agents based on
the proven isothiazolone chemistry of Rohm and Haas Company.
They are effective at very low concentrations in controlling both the planktonic and surface growth of bacteria,
fungi and algae and have been produced specifically for water treatment and paper mill applications.
Rohm and Haas Company have developed an unrivalled package of regulatory approvals and environmental fate,
toxicology, and performance data to support the use of KATHON WT in water treatment applications.
For some years, Rohm and Haas Company have manufactured KATHON WT at facilities approved according to the
internationally recognised Quality Standard ISO 9002 (equivalent to BS5750 Part 2). This reflects the commitment
of Rohm and Haas to supply high quality products for its customers.
This technical bulletin provides efficacy, toxicology and environmental fate data to allow the safe and effective use
of KATHON WT.
* Unless otherwise specified "KATHON WT" is used to denote the KATHON WT group of biocides, which includes
KATHON WT, WTE and WTA.
1 - Performance
• KATHON WT microbicides offer numerous outstanding advantages:
Rapid inhibition of growth and macromolecular synthesis:
KATHON WT causes immediate inhibition of growth on coming in contact with a microorganism. The growth
inhibition rapidly becomes irreversible and results in cell death. Even before death occurs, the KATHON treated
organism is unable to synthesize degradative enzymes or the exopolymers which facilitate adhesion and biofilm
formation.
Broad spectrum activity:
KATHON WT controls the wide variety of algae, bacteria and fungi found in industrial water systems. Such a broad
spectrum product reduces inventory and handling costs, lowers operator training expenses and lessens the risk of
dosing error.
Effective at low concentrations:
Effective control of such a wide variety of microorganisms at levels as low as 1 ppm active ingredient by KATHON
WT, provides an unrivalled and cost-effective treatment.
Effective against biofilm:
KATHON WT readily penetrates the surface of adhering biofilm to give effective control of sessile microorganisms.
Biodegradable/non-persistent in the environment:
When diluted below use concentrations, KATHON WT, WTA and WTE are readily biodegradable. Their
decomposition does not lead to the presence of chlorinated organics in the environment.
Effective over a wide pH range:
KATHON WT microbicide exhibits excellent performance over a broad pH range, even in alkaline water systems.
Water soluble:
KATHON WT is easily incorporated into formulations.
Compatibility:
KATHON WT is compatible with chlorine, corrosion and scale inhibitors and most anionic, cationic and non-ionic
formulations at normal use levels.
Non-surface active:
KATHON WT is non-foaming.
Infrequent dosing:
KATHON WT remains active for long periods of time in the water system, resulting in low service costs.
Easily deactivated:
Spills of the concentrated active components of KATHON WT are readily deactivated to non-toxic substances by
the addition of a slightly acidic solution of sodium metabisulphite or sodium bisulphite.
Low toxicity:
Extensive toxicological testing has shown KATHON microbicides to be of low toxicity at recommended use levels.
Continued testing ensures that potential risks are well defined.
2 - Chemical and Physical Properties
• The active ingredient of KATHON WT biocides is a mixture of two isothiazolones identified by
the IUPAC system of nomenclature as:
The chemical composition, physical and chemical properties of KATHON WT, KATHON WTA and KATHON WTE
microbicides are shown in Table 1.
Table 1 - Composition and properties of KATHON WT microbicides
(these values do not constitute specifications)
KATHON WT KATHON WTA KATHON WTE
▪5-chloro-2 methyl-4-isothiazolin-3-one
▪2-methyl-4-isothiazolin-3-one
Typical value active ingredients
13.9%
1.5%
1.5%
Inert Ingredients 28.0% 3.0% 3.0%
Water to 100% to 100% to 100%
Typical properties
Appearance Clear to slightly hazy liquid
Colour Amber-gold Pale yellow Pale yellow green
Odour Mild Mild Mild
Specific gravity (20°C) 1.32 1.02 1.02
pH (as supplied) 2-4 3-5 3-5
Viscosity (cps) 15°C
25°C
35°C
19.0
16.0
14.5
19.0
16.0
14.5
19.0
19.0
19.0
3 - Stability/Compatibility
• KATHON is stable over the wide range of conditions found in cooling water and paper mill
applications.
Product as supplied:
KATHON WT and WTE microbicides are stable as supplied for at least a year at ambient temperatures and for 6
months at 50°C. We recommend, however, that KATHON WTA is stored at 25°C or below for a maximum period of
6 months. Generally, storage conditions appropriate for industrial chemicals should be employed, avoiding
exposure to extremes of temperature.
At use levels:
The performance of biocides in industrial water systems is dependent on their stability. Several factors can
influence the rate of degradation including water hardness, pH and temperature. The stability of KATHON WT is
actually enhanced in hard water conditions. At normal use levels in water treatment systems, KATHON WT biocides
are biologically and physically compatible with:
• anionic, cationic and non-ionic surfactants
• corrosion and scale inhibitors
• chlorine (Table 2)
• majority of standard paper mill additives.
Figure 1 shows the excellent stability of KATHON WT compared with competitive biocides at different levels of pH,
temperature and total water hardness. This is dealt with in greater detail in the section on stability/ compatibility.
In addition to its excellent stability at use levels, KATHON WT has the advantage that, when diluted well below its
use level, it is readily biodegradable.
Table 2 - Stability of 10 ppm active ingredient KATHON WT in the presence of 1.0 ppm free residual
chlorine
Temperature: 27°C ; pH 7.5.
Fig. 1: Stability of KATHON WT vs. competitive biocides at different levels of temperature and water
hardness over a pH range 5.5-9.5
TIME (hours) FREE CHLORINE (ppm) KATHON WT (ppm AI)
0 1.0 10.0
2 1.0 10.0
4 1.0 9.7
6 1.0 9.8
69 0.1 9.1
* Total Water Hardness
DBNPA = 2.2-dibromo-3-nitrilopropionamide
GLUT = glutaraldehyde
MBT = methylene (bis) thiocyanate (data not yet available at pH 5.5)
4 - Antimicrobial Properties
• KATHON WT is an extremely effective, broad spectrum microbicide which causes an immediate
inhibition of growth on coming in contact with a microorganism.
KATHON WT rapidly interacts with proteins within the cell, causing an inhibition of respiration and ATP synthesis,
which results in an inability to synthesize biopolymers or catabolize substrate. Growth inhibition rapidly becomes
irreversible and results in cell death as essential proteins are progressively oxidized. Even before cell death occurs,
the KATHON-treated organisms are unable to synthesize either biodegradative enzymes or the exopolymers which
facilitate microbial adhesion and biofilm formation.
Minimum inhibitory concentrations
Tables 3-6 show the minimum inhibitory concentrations (MIC) of KATHON WT active ingredient against
microorganisms in test-tube and microtitre plate assays i.e. the lowest concentration which will inhibit microbial
growth.
This data demonstrates broad spectrum activity against all types of fouling microorganisms e.g. fungi, bacteria,
and algae. The methods used to obtain this data are useful for screening antimicrobial substances under
standardized laboratory conditions, in nutrient rich growth media. Therefore the effective levels of active
ingredient derived from these tests do not necessarily translate into the most efficacious use levels for particular
applications.
Antimicrobial properties of a water treatment biocide
Many water treatment biocides have "gaps" in their activity spectra i.e. they may be good fungicides but poor
algicides or bactericides. One biocide which can perform the function of two or three different products, saves both
time and money and reduces the chances of dosing errors. A broad spectrum biocide, such as KATHON WT, which
prevents the growth of, or kills organisms causing surface fouling, at low concentrations, is essential in industrial
water treatment.
Table 3 - Minimum inhibitory concentrations of KATHON WT vs fungi a
ORGANISM ATCC N° ACTIVE INGREDIENT (ppm)
*Aspergillus foetidus 16878 8
*Aspergillus niger 9642 9
*Aspergillus oryzae 10196 5
Candida albican (yeast) 11651 5
Chaetomium globosum 6205 9
*Cladosporium resinae (Hormoconis resinae) 11274 5
Gliocladium fimbriatum QM7638 9
Lentinus lepideus 12653 4
Gloeophyllum trabeum 11539 6
*Mucor rouxii R and HL5-83 5
>*Penicillium funiculosum 9644 5
>*Penicillium variabile (glaucum) USDA 2
Phoma herbarum (pigmentivora) 12569 2
*Aureobasidium pullulans 9348 5
*Rhizopus stolonifer 10404 5
> Rhodotorula rubra (yeast) 9449 2
Saccharomyces cerevisiae (yeast) 2601 2
Trichophyton mentagrophytes (interdigitale) 9533 5
Table 4 - Minimum inhibitory concentrations of KATHON WT vs bacteriaa
> Microorganisms causing fouling of cooling towers.
* Microorganisms associated with slime deposits in paper-making processes.
a: The bacteriostatic and fungistatic tests were performed by serially diluting the biocide in trypticase-soy broth
followed by a 1:100 inoculation with 24-hour broth cultures of test bacterium or fungal spore suspension
(prepared from 7-14 day culture slants washed with 7 mls of deionized water). Minimum inhibitory
concentration levels were determined visually after 2 days incubation at 37°C for bacteria and 7 days
incubation at 28-30°C or fungi.
• Biofilm.
A considerable difference exists between the efficacy of a biocide against free-living or planktonic microorganisms
and surface-attached or sessile microorganisms. Sessile microorganisms build up on process surfaces that are in
continual contact with water, to form biofilms, which may vary from the more obvious slimy or filamentous layers,
to discrete deposits barely visible to the naked eye.
Biofilms consist of complex populations of sessile microorganisms (including bacteria, fungi, protozoa and algae)
inorganic and organic debris bound together by an extracellular microbial adhesive1,2 (Fig. 2). The polysaccharide
matrix protects microorganisms against rapid environmental changes, including the addition of many biocides and
other water treatment chemicals, making them more difficult to kill than their freeliving counter-parts. Some
biocides may also be deactivated by adsorption to organic and/or inorganic debris within the biofilm itself.
Not only do surface-attached microorganisms outnumber planktonic populations by several orders of magnitude,
but they are also the direct cause of most problems in industrial cooling water systems, air washers and paper
mills. These include:
ORGANISM ATCC N° ACTIVE INGREDIENT (ppm)
GRAM-NEGATIVE
Achromobacter parvulus 4335 2
*Alcaligenes faecalis 8750 2
Azotobacter vinelandii 12837 5
*Enterobacter aerogenes 3906 5
Escherichia coli 11229 8
>*Flavabacterium suaveolens 958 9
> Nitrobacter agilis 14123 0.1
*Proteus vulgaris 8427 5
>*Pseudomonas aeruginosa 15442 5
>*Pseudomonas cepacia Gibraltar 165 0.75
>*Pseudomonas fluorescens 13525 2
>*Pseudomonas oleoverans 8062 5
Shigella sonnei 9292 2
GRAM-POSITIVE
>*Bacillus cereus var. mycoides R and HL5 2
>*Bacillus subtilis R and HB2 2
Brevibacterium ammoniagenes 6871 2
Cellulomonas sp. 21399 6
>Sarcina lutea 9341 5
*Staphylococcus aureus 6538 2
*Staphylococcus epidermidis 155 2
Streptomyces albus 3004 1
Energy loss due to fouling
• increased heat transfer resistance
• filter blocking
• decreasing fluid flow/increasing pressure drop in pipes
Microbial-induced corrosion
• of unprotected metal surfaces beneath the biofilm
Decreased manufacturing efficiency
• breakaway biofilm interferes in paper manufacture
• increased stoppages for cleaning and maintenance of equipment
Failure of other water treatment chemicals
• biodegradation of additives such as corrosion inhibitors
Potential health effects
• biofilm may harbour pathogenic or potentially pathogenic organisms e.g. Legionella and Pseudomonas spp.
Table 5 - Minimum inhibitory concentrations of KATHON WT vs algae b
Table 6 - Minimum inhibitory concentrations of KATHON WT vs blue green bacteria b
> Microorganisms causing fouling of cooling towers.
b: A 96-well microtitre plate assay using two-fold serial dilutions in growth media, was employed to determine
MIC values against algae and blue green bacteria. Microorganisms used as inoculum were grown up on an
algal-cyanobacterial medium under constant agitation and with a 16 hour illumination cycle. MICs were
determined visually (using a microtitre plate reader) after 14-21 days incubation at 25°C under constant
illumination.
ORGANISM ACTIVE INGREDIENT (ppm)
CHLOROPHYTA (GREEN ALGAE)
>Chlorella oleofaciens 0.12
>Chlorella pyrenoidosa 0.03
Scenedesmus quadicauda 1.0
Selenastrum capricornutum 0.25
>Ulothrix fimbriata 0.63
>Ulothrix acuminata 0.63
CYANOPHYTA/CYANOBACTERIA
Anabaena flos-aquae 0.03
Nostoc commune 0.12
>Oscillatoria prolifera 0.08
Phormidium luridum 0.12
Synechococcus leopoliensis 0.50
Schizothriz calcicola 0.31
Scytonema hofmanni 0.16
Calothrix parienta 0.31
Microcystis aeruginosa 0.16
• The need for activity against biofilm.
An industrial water treatment biocide must be active against biofilm. In spite of this, many biocides are still only
tested against planktonic microorganisms (see Cooling Water Microbicide section). Rohm and Haas have been at
the forefront of research into sessile testing* and have independently developed and tested two laboratory
methods for monitoring the use of biocides to control biofouling in industrial water distribution systems, namely:
• model cooling towers
• circulating biofilm loops
KATHON WT is not only effective in killing microorganisms in existing biofilms, but will also prevent biofilm
regrowth when regularly dosed into a clean system.
KATHON WT is one of the few microbicides extensively tested against biofilm organisms during its development.
A more comprehensive discussion of biofouling, the problems it causes and the efficacy of KATHON WT against
biofilms, are given in the Cooling Water and Paper Mill Microbicide sections.
* See External Rohm and Haas Publications list at the end of this bulletin.
5 - Comparative Efficacy
• Field and laboratory evaluation.
KATHON WT has been evaluated against competitive biocides in extensive laboratory tests and field trials. Results
show that it easily out-performs its nearest competitors (Fig. 3).
It produces excellent control against sessile aerobic and anaerobic microorganisms, in both industrial cooling
systems (Fig. 4 and Table 7) and as a paper mill slimicide (Fig. 5). Field trials in an industrial air washer have also
proved its excellence as a microbicide (Table 8).
It is effective over a wide pH range and is therefore ideal for use in the alkaline conditions that exist in multi-cycle
cooling towers and modern papermaking.
It is attractive economically because low levels and infrequent doses can be used successfully.
Fig. 3 : Comparative efficacy of KATHON WT and alternative water treatment biocides against biofilm in
model cooling towers (viable cells per sq cm). The approximate cost of alternative biocide treatment
have been calculated in comparison with that of 1 ppm AI KATHON WT and are expressed as costequivalents

Fig. 4 : Effect of KATHON WT on naturally occurring microbial populations in an industrial cooling
tower
Table 7 - Effect of KATHON WT on microbial populations in an industrial cooling tower
a: % Reduction based on initial count.
AREA
SAMPLED
MICROORGANISM
INITIAL COUNT
% REDUCTIONa AFTER:
3 Weeks
Dose
9 ppm AI
5 Weeks
Dose
1 ppm AI
5 Weeks
Dose
0.5 ppm AI
Basin Water Bacteria
Fungi
Algae
1.30 x 106/ml
2.80 x 102/ml
3.93 x 102/ml
75
94
96
53
93
88
86
91
–
Slats Bacteria
Fungi
Algae
2.79 x 109/cm2
1.64 x 105/cm2
3.44 x 105/cm2
98
99.5
–
97
94
88
94
99.2
96
Distribution
Boxes
Bacteria
Fungi
Algae
4.58 x 1010/cm2
4.19 x 104/cm2
2.06 x 107/cm2
99.9
99.4
>99.99
97
93
92
95
93
99.98
Fig. 5 : Comparative efficacy of KATHON WT and carbamate in a paper mill producing newsprint
Figure 5 illustrates a case history of biocide treatment in a newsprint mill where biocide addition was at the broke
towers. Using carbamate, bacterial counts in the broke pulp were unacceptably high. After changing to a costequivalent
level of KATHON WT, bacterial counts in the broke were significantly reduced and downtime due to
contamination was minimized.
Table 8 - Effect of KATHON WTE on the microbial populations in an industrial air washing system a,b
a: System Parameters
Volume of water: 945,000 litres
Retention time: 2.5 cycles (19 days based on blowdown)
pH: 7.6
KATHON WTE level: 1.0 ppm AI
Dose schedule: Initial dose: 60.5 litres KATHON WTE charged into common sump (60 ppm as supplied)
Subsequent doses: 7.5 litres KATHON WTE 1.5% charged into common sump based on
blowdown
b: Visual Evaluation
KATHON WTE maintained a clean system. No problems of odour or foaming were encountered during or after the
trial
c: Most probable number of sulphate reducing bacteria/ml
d: 0 = none detected
COMMON SUMP AIR WASHERS
Total Count
/ml
Fungi/ml SRB/ml c Total Count
/ml
Fungi/ml SRB/ml c
Initial Count
(No KATHON WTE)
7.5 x 105 70 6.3 x 102 1.0 x 106 30 7.4 x 102
After 1st dose
3 hours
24 hours
2.2 x 105
6.0 x 103
0d
0
0
9
1.7 x 105
1.0 x 103
0
1
0
0
After 2nd dose
3 hours
24 hours
9.0 x 103
1.0 x 103
8
0
80
0
1.2 x 104
8.0 x 103
0
0
35
0
After 3rd dose
3 hours 7.0 x 103 0 0 1.0 x 103 0 0
6 - Application Areas
• KATHON WT is ideally suited to meet the requirements of an industrial water treatment biocide.
KATHON WT microbicide is not deactivated by suspended organic matter, and is compatible with other water
treatment additives, including chlorine. With the recent change of many cooling towers and paper mills to alkaline
operating conditions, it is important to use a biocide such as KATHON WT, which remains stable at higher pH
values. KATHON WT is of low toxicity at use levels, easily deactivated and biodegradable. In addition to all these
essential properties, KATHON WT is cost-effective.
Table 9
APPLICATIONS MAXIMUM USE LEVEL
(ppm active ingredients)
1. Industrial cooling water systems 15.0
2. Industrial air washers with efficient
mist-eliminating system
15.0
3. Paper mill slimicides 15.0
• Cooling tower microbicide.
KATHON WT is a broad spectrum
biocide, active against microorganisms
in the biofilm. It is cost-effective and
ideally suited for use in todays alkaline,
multi-cycle towers (Fig. 4). A
concentration of KATHON WT as low as
1 ppm active ingredient, single-dosed
every 3-7 days (depending on
blowdown rate) is often sufficient to
control severe microbiological fouling.
• Maximum use levels.
These maximum use levels relate
to the level of KATHON WT active
ingredients which may be
constantly present in the
applications described. Lower
maximum use levels may be
appropriate in some instances to
satisfy local environmental
discharge/regulatory requirements.
For further information on
maximum use levels, please refer
to the Safety Guidelines Bulletins.
• Air washer microbicide.
KATHON WT is very effective in
controlling microbial growth in
industrial air washing systems
(Table 8).
• Paper mill slimicide.
KATHON WT is a high performance
paper mill slimicide with a broad
spectrum of activity which can cope
with the rapid changes in microbial
flora that occur in different
papermaking systems. It
penetrates and kills
microorganisms in the biofilm and
is not inactivated by the high level
of suspended organic solids found
in paper mill water. It also provides
cost-effective microbial control
(Fig. 5).
7 - Toxicology and Environmental Fate
• Rohm and Haas Company, one of the foremost specialty chemical manufacturers, takes every
measure to ensure that its products are safe for both people and the environment.
Toxicology
In line with this policy, Rohm and Haas provide comprehensive toxicological data for KATHON WT, which shows
that it is of low toxicity at use-levels.
Environmental fate
With the tightening of legislation governing the quality of industrial effluent, a major consideration in the choice of
a biocide for industrial water treatment is its fate in the environment. This is discussed in more detail in the
section on Environmental Fate and some of the original research is published in the Journal of Agricultural and
Food Chemistry, 23, 1060-1075, 1975. Reprints are available on request.
• KATHON WT has minimal environmental impact because of the following properties:
• high performance product
• very low use levels
• readily biodegradable/non-persistent in the environment
• does not lead to the presence of chlorinated organics
• does not affect performance of waste water treatment plants
KATHON WT has been shown to be environmentally acceptable by a variety of test procedures. The criteria for
acceptability is beyond the most stringent control parameters introduced by regulatory authorities.
This unique combination of properties makes KATHON WT a first choice for any water treatment programme.
Fig. 7 : Dissipation of KATHON WT AI in river water
8 - Current Regulatory Status
• The list below is intended to assist you and your customers to comply with prevailing regulatory
controls. It illustrates the status of KATHON WT microbicide in those countries where specific
approvals are required.
Current regulatory status
Other grades of KATHON microbicides based on the same active ingredients as KATHON WT have obtain FDA or
BGA approvals allowing their use as preservatives in latex which is employed in the production of adhesives and
paper and board for contact with dry, aqueous and fatty foods.
For further details of those approvals, please contact your local Rohm and Haas Sales Office.
Table 10
a: These products have different designations in the USA.
It should be borne in mind that these clearances apply to KATHON microbicides as submitted by Rohm and Haas
Company and that formulations containing other ingredients may need to be resubmitted for approval.
9 - References
• General.
1. Characklis, W.G. and Cooksey, K.E. (1983). Biofilms and microbial fouling. Adv. Appl. Microbiol., 29, 93-138.
2. Costerton, J.W., Geesey, G.G. and Cheng, K. (1978). How bacteria stick. Sci. Am., 238, 86-96.
• External Rohm and Haas publications.
• Costerton, J.W. and Lashen, E.S. (1984). Influence of biofilm on efficacy of biocides on corrosion-causing
bacteria. Mater. Perform. 23,13-17.
• Haack, T.K., Lashen, E.S. and Greenley, D.E. (1988). The evaluation of biocide efficacy against sessile
COUNTRY PRODUCT REGULATORY
CLEARANCE
APPLICATION NOTES
Germany KATHON WT and
WTE Active
Ingredient (AI)
BGA Rec. XXXVI
“Paper and paper
board"
As slimicide in
manufacture of
food contact
paper
As a slimicide at a
maximum level of
4 ppm AI in dried
fibre
Italy KATHON WT and
WTE AI
Decree August 7,
1987 N° 395
Food contact
paper
At 0.1 ppm AI
max. extractable
from paper
Netherlands KATHON WT
KATHON WTA
N° 9926 N August,
1985
N° 10034N
Paper mill and
cooling water
slimicide
Not for food
contact
Sweden KATHON WTE Swedish
Chemicals
Inspectorate
N° 3401
Paper mill
slimicide
Can be used in
manufacture of
food contact
paper
Switzerland KATHON WT and
WTE AI
EGA Substance
List N° 49466
Class III
All
USA KATHON WT and
WTEa
KATHON WTa
KATHON WT and
WTEa AI
EPA 707-128
707-133
EPA 707-132
FDA 21 CFR176.
300
Cooling towers
and air washers
Paper mill slimicide
Paper slimicide
Up to max. use
level of 1.4 lb
AI/ton dry wgt.
paper
KATHON is a trademark of Rohm and Haas Company, or of its subsidiaries or affiliates.
These suggestions and data are based on information we believe to be reliable. They are offered in good faith, but without guarantee, as
conditions and methods of use of our products are beyond our control. We recommend that the prospective user determines the suitability of
our materials and suggestions before adopting them on a commercial scale.
Suggestions for uses of our products or the inclusion of descriptive material from patents and the citation of specific patents in this publication
should not be understood as recommending the use of our products in violation of any patent or as permission or license to use any patents of
the Rohm and Haas Company.
For further details, please contact your local Account Manager or local Business Representative.
microorganisms. In Developments in Industrial Microbiology, vol. 29. (J. Indust. Micro., Suppl. N° 3)
pp. 247-253.
• Haack, T.K., Shaw, D.A. and Greenley, D. E. (1986). Isothiazolones preserve starch-based drilling muds. Oil
and Gas J., January 6th, 1986.
• Krzeminski, S.F., Brackett, C.K. and Fisher, J.D. (1975). Fate of microbicidal 3-isothiazolone compounds in the
environment : Modes and rates of dissipation. J. Agric. Food Chem., 23, (6), 1060-1068.
• Krzeminski, S.F., Brackett, C.K., Fisher, J.D. and Spinnler, J.F. (1975). Fate of Microbicidal 3-isothiazolone
compounds in the environment: Products of degradation. J. Agric. Food Chem., 23, (6), 1068-1075.
• McCoy, W.F. and Lashen, E.S. (1985). Biocide efficacy against sessile microorganisms in laboratory model
cooling towers. Proc. U.K. Corrosion '85, Harrogate. 259-269.
• McCoy, W.F. and Lashen, E.S. (1986). Evaluation of industrial biocides in laboratory model cooling towers.
Proc. Ann. Meet Cooling Tower Inst., Paper N° TP-86-17.
• McCoy, W.F., Ridge, J.E. and Lashen, E.S. (1986). Kinetic analysis of a new delivery system for cooling
towers. Proc. 47th Annual Meeting The International Water Conference, Pittsburg, PA.
• McCoy, W.F., Wireman, J.W. and Lashen, E.S., (1986). Efficacy of methyl-chloro/methylisothiazolone biocide
against Legionella pneumophila in cooling tower water. J. Indust. Micro., 1, 49-56.
• Ruseska, I., Robbins, J., Costerton, J.W. and Lashen, E.S. (1982). Biocide testing against corrosion-causing
oilfield bacteria helps control plugging. Oil and Gas J., 253-264.
• Tanner, R.S., Haack, T.K., Semet, R.F. and Greenley, D.E. (1985). A mild steel tubular flow system for biofilm
monitoring. Proc. U.K. Corrosion '85, Harrogate. pp. 259-269.
• Williams, T.M. (1988). Growth and control of biofouling microorganisms in modified laboratory cooling towers.
Proc. 2nd Venezuelan Corrosion Conference, Venezuelan Central University, Caracas, Venezuela.
Acknowledgements
The electron micrograph which forms Figure 2 has been reproduced by kind permission of the Fouling Forum,
Harwell Laboratories, U.K. A.E.A. The photograph on page 16 has been reproduced by kind permission of New
Thames Paper Company, part of UK Paper, U.K.
©Rohm and Haas, 2006 All rights reserved.
December 2000
BIO.KATHON WT GE.PB. E.